Integrated: 8309268: C2: "assert(in_bb(n)) failed: must be" after JDK-8306302

[Emanuel Peter]

On Thu, 1 Jun 2023 16:19:41 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> This is the fix to a regression caused in the CMoveV fix JDK-8306302.
> 
> I had implicitly assumed that all `Cmp` in the loop also have their `in(1)` inside the loop (`in_bb`). This is not always true, and hence we hit the assert.
> 
> **Solution**
> 
> However, we know that at least one of the two inputs of a `Cmp` must also be in the loop, else the `Cmp` would float outside the loop. So if `in(1)` is not in the loop then we can just pick `in(2)` for the `velt_type`.
> 
> **Testing**
> I added 2 regression tests that were provided in the bug, and also extended `TestVectorConditionalMove.java` (though it is currently problemlisted because of an IR framework bug). This extension also triggered the assert, and now properly vectorizes.
> 
> I tested up to tier6 and stress testing. I ran the tests both with `TestVectorConditionalMove` problemlisted and without the problemlisting.

This pull request has now been integrated.

Changeset: 22a9a86b
Author:    Emanuel Peter <epeter at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/22a9a86be088a3e92b231e7180a134f63716cc87
Stats:     135 lines in 3 files changed: 132 ins; 0 del; 3 mod

8309268: C2: "assert(in_bb(n)) failed: must be" after JDK-8306302

Reviewed-by: rcastanedalo, kvn, thartmann

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PR: https://git.openjdk.org/jdk/pull/14268